Hi HN! This has been posted a few months ago (by someone else), but it wasn't really finished back then. The feedback I got here last time has helped a lot to improve all sorts of things. Looking forward to your comments!
I have only one minor issue: the REPL scrolling conflicts with the default scrolling acceleration on macOS. So just a very small movement on the trackpad and it scrolls all the way up or down. I believe this is due the "jquery-mousewheel" plugin [1].
Old discussion: https://news.ycombinator.com/item?id=13909631